Continuing from my RCIA notes:
It is almost impossible to overstate the anti-Catholicism of colonial Americans. It was brought with them from England, of course. Much of the sense of being a Briton was tied up with being Protestant. “Rule Britannia” expresses the anti-French, anti-Catholic sentiments of the British people at this time: When the chorus of that song proclaims that “Britons never will be slaves” it did not indicate that Britons would never wake up as black men and women treated as chattel. It meant that Britons would not wake up subject to the absolute monarchy and priestcraft of France. In America, geography added to the prejudice. The French and Spanish settlements surrounded the English colonies, and the recurrent wars between them did little to quell the anti-Catholic prejudices of the English settlers. This prejudice was especially the case with the French and Indian War from 1754-1763. The Battle of Culloden in 1746 had been the last attempt by the Stuarts to reclaim the throne and the memory was fresh in the minds of the colonists. Now, they had the chance to help throw off their menacing neighbor to the North and West, and the colonists rallied to the British standard and helped win the war which ejected the French from North America.
The anti-Catholicism was not only legal. In colonial America, by far the most frequently printed materials were sermons and while Puritans in Massachusetts shared little in common with Anglicans in Virginia, all were united in their hatred of Catholics. Indeed, the Anglican Church which enjoyed legal establishment in the southern colonies was very low church and in the years before the American Revolution, there was a great hue and cry against the possibility that there might be sent to America an Anglican bishops. Anglican pastors denounced this. Bishops were seen as too Romish, the kind of thing the Church of England would be better without.
The dominant political ideology of the colonists was what the great historian of the Revolution Bernard Bailyn has called “Country Whig” political philosophy. This was the most anti-Catholic of all British political ideologies, very anti-clerical, very republican, with roots in the Commonwealth teachings of Cromwell.